<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="App">
    <h1>{{a}}</h1>
    <div v-if="a === 10">显示</div>
    <button @click="a++">点击</button>
</div>
</body>
<script src="./vue.js"></script>
<script>
    const {createApp,ref } = Vue;
    const App = createApp({
        setup() {
            let a = ref(0)
            return{
                a
            }
        }
    }).mount('#App')
</script>
</html>